Problem

The Spring Boot tutorials contained deprecated API usage patterns that could lead to performance issues and inconsistent behavior:

1. Batch modules: Creating new ObjectMapper instances repeatedly in method calls
2. MongoDB module: Using deprecated TextIndexDefinitionBuilder constructor

Changes Made

Fixed ObjectMapper Anti-pattern

Before:

private JsonItemReader<User> reader() throws MalformedURLException {
    JacksonJsonObjectReader<User> jsonObjectReader = new JacksonJsonObjectReader<>(User.class);
    jsonObjectReader.setMapper(new ObjectMapper()); // ❌ Creating new instance every time
    return new JsonItemReaderBuilder<User>()...
}

After:

private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper(); // ✅ Single static instance

private JsonItemReader<User> reader() throws MalformedURLException {
    JacksonJsonObjectReader<User> jsonObjectReader = new JacksonJsonObjectReader<>(User.class);
    jsonObjectReader.setMapper(OBJECT_MAPPER); // ✅ Reusing static instance
    return new JsonItemReaderBuilder<User>()...
}

Fixed TextIndexDefinitionBuilder Anti-pattern

Before:

import org.springframework.data.mongodb.core.index.TextIndexDefinition.TextIndexDefinitionBuilder;
// ...
new TextIndexDefinitionBuilder().onFields("name", "publisher").build() // ❌ Deprecated constructor

After:

import org.springframework.data.mongodb.core.index.TextIndexDefinition;
// ...
TextIndexDefinition.builder().onFields("name", "publisher").build() // ✅ Modern static factory method

Modules Updated

• batch-rest-repository: Fixed ObjectMapper instantiation in JSON reader
• batch-skip-step: Fixed ObjectMapper instantiation in JSON reader
• data-mongodb-full-text-search: Fixed TextIndexDefinitionBuilder usage in both test and implementation files

Verification

• ✅ All affected tests pass with new implementations
• ✅ No functionality regressions introduced
• ✅ Performance improved by eliminating repeated object instantiation
• ✅ Code now follows modern Spring Boot and Spring Data MongoDB best practices

This change improves code quality by eliminating deprecated patterns, reducing memory allocation overhead, and ensuring consistent behavior across the application.

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